Work is being undertaken to learn more about the pathogenesis of trachoma, a blinding chlamydial conjunctival infection. An animal model has been developed in monkeys in which repeated episodes of infection have been found to be important in producing the disease.. Future studies will include examining the effect of immunosuppression, both on the initiation of the disease and on its continuation. Studies also will investiate the effect of superimposed bacterial infection on the severity and progression of the chlamydial infection. Attempts will be made to localize the components of the immune response to the chlamydial infection by immunofluorescent techniques, and to study the role of the secretory immune system in conjunctival infection.